After years of designing and building my own boats, I may have come up with an answer.

I have a wood boat hull that Is 29a€ Inches long and 8.25a€ In beam with 2-3a€ Inches In freeboard or (wall height) sides of boat hull. I was able to successfully run this v-bottom hull on two 2100 Mah 7 cell NiCad packs. That comes out to about 16.8 volts. This boat was really moving even thou the hull was heavy. Around 4 lbs or more. To keep the boat from overheating I would need the following

1. Motor with high torque (villain 23 turn) $18.00

2. Water jacket for motor

3. Electronic speed controller that could handle high amperage (60 amps) $60

4. Gearbox $20

5. Various size props

6. Battery pack with high discharge rate

I wanted a boat that was fast without spending a lot of money. I ran Into all the usual problems of batteries, motors, and esca€™s overheating. If things over heat, that Is usually a sign that your putting too much of a load on the motor which In turn Increases amperage. It would be like you riding your bike In high gear while youa€™re riding up a steep hull. To keep your boat from overheating

1. Buy various size props Is a good start. There usually Inexpensive Investment. The smaller prop you use, the less load on the motor.

2. Gearboxes help reduce amperage and give your motor more torque and longer run times. Gearboxes also let you come up with various power combinations. I used an MPI gearbox made for R/C planes. If you had a small pinion gear on your motor leta€™s say 13 teeth, and the spur gear on the gearbox were 50, which would give you a ratio of 3.84.

50/13=3.84 If you had 17 tooth pinion on the motor with the same spur 50 tooth spur gear the ratio would be 2.94. The smaller the ratio numbers the faster the prop will be spinning. With tug boats, you want a gear box with a high ratio like 6:1,7:1,8:1. You could using larger props as well.

Examples

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